Linear and rotational movement sootblowers have been available for some time, including devices that rotate the nozzles of its extendable lance so that the path of the cleaning fluid traces a helical path along the surfaces of the boiler tubes to be cleaned. U.S. Pat. No. 4,399,773 (by Schwade) discloses a sootblower having a slip coupling to allow rotation without a corresponding linear movement, along with a timer and limit switch to cause the nozzles of the lance tube to stop at different rotational positions at the end of each cycle. The Schwade device thereby traces different helical paths every time the lance goes through an extension and retraction cycle, so that it is possible to clean a greater area of the boiler tubes through several extension/retraction cycles. Several other patents also vary the rotation and travel of the nozzles of the lance tube to establish different helical blowing paths, including U.S. Pat. No. 3,604,050, U.S. Pat. No. 4,803,959, U.S. Pat. No. 5,065,472, U.S. Pat. No. 4,222,144, U.S. Pat. No. 5,097,564, and U.S. Pat. No. 2,442,045.
In addition to disclosures in patents, certain commercial sootblowers are presently available which establish different cleaning paths, including a Diamond Power IK sootblower having a feature called "Progressive Helix," and a Copes IK Long Retract that includes a device called "Random Cleaning."
Other conventional sootblowers achieve varying cleaning paths by using variable rates of rotation or axial movement of their lance, including disclosures in patents U.S. Pat. No. 4,492,187, U.S. Pat. No. 5,337,438, U.S. Pat. No. 5,337,441, U.S. Pat. No. 3,230,568, and U.S. Pat. No. 2,722,033.
The conventional sootblowers disclosed in the above patents and in the commercially-available products do not provide the user with easily adjustable control over the cleaning paths to clean the boiler tube surfaces with a minimum number of lance extension/retraction cycles. In addition, the conventional sootblowers having various types of lost motion devices do not allow for complete adjustability at the beginning of the extension and retraction strokes so that the variety of cleaning paths are somewhat limited.